<html>
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<?php 
		define(PI, 3.14);
		function mainji($$banjing){
			return PI*$banjing*$banjing;
		}
		echo "<br>".mainji(3);
	 ?>
	
</body>
</html>